In any water distribution system, fire hydrants are a direct access to public drinking water. Fire hydrants are attached to water mains to provide fire departments with quick access to a water source when needed to combat a fire. Any unauthorized access to this system presents a danger to the public. If fire hydrants are opened as recreational devices, this reduces water and pressures needed by the fire department in case of a fire emergency. Moreover, contractors are known to illegally take water from hydrants without using a meter and a backflow device, which not only costs the public money but substantially increase the danger of contaminating water systems. The amount of water consumed by contractors can be substantial when constructing large buildings or numbers of dwellings, or when simply taking water to fill swimming pools. In addition, terrorist threats to water systems are becoming a serious concern. In an attempt to address these problems, fire departments resort to fire hydrant locks that over time become increasingly subject to defeat as special operators for these locks are stolen or otherwise slip into unauthorized hands. Accordingly, there is a need for fire hydrant locks which minimize, for at least a substantial number of years, successful attempts to defeat the locks by unauthorized people.